# std::plus<void>

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< cpp‎ | utility‎ | functional

Defined in header `<functional>` |  |
template<> class plus<void>; |  | (since C++14)

std::plus<void> is a specialization of std::plus with parameter and return type deduced.

### Member types

Type | Definition
`is_transparent` | unspecified

### Member functions

operator() | returns the sum of two arguments (public member function)

## std::plus<void>::operator()

template< class T, class U > constexpr auto operator()( T&& lhs, U&& rhs ) const -> decltype(std::forward<T>(lhs) + std::forward<U>(rhs)); |  |

Returns the sum of lhs and rhs.

### Parameters

lhs, rhs | - | values to sum

### Return value

std::forward<T>(lhs) + std::forward<U>(rhs).

### Example

Run this code

    #include <functional>
    #include <iostream>

    int main()
    {
        auto string_plus = std::plus<void>{}; // “void” can be omitted
        std::string a = "Hello ";
        const char* b = "world";
        std::cout << string_plus(a, b) << '\n';
    }

Output:

    Hello world

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